My thoughts as well.

Also, every time I visit a new airport in the US, it comes to mind how damn near every medium-sized city has a sprawling, fairly clean, air-conditioned airport, with shops and seating, usually open 24 hours. The Amtrak stations in those same cities, if they exist, are usually one-room buildings that close for most of the day. The Greyhound station is nowadays usually just a spot on the side of the road.

Why the disparity? I guess there are just that many more people flying than taking the bus or train? (Built-in security and a generally richer clientele certainly help too, I'm sure)